linux-kernel - Re: [PATCH v2 5/6] ARM: EXYNOS: Fix suspend/resume sequences

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Date:	Tue, 15 Jul 2014 13:19:29 +0200
From:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:	Tomasz Figa <tomasz.figa@...il.com>
Cc:	Tomasz Figa <t.figa@...sung.com>,
	linux-samsung-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Kukjin Kim <kgene.kim@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Abhilash Kesavan <kesavan.abhilash@...il.com>
Subject: Re: [PATCH v2 5/6] ARM: EXYNOS: Fix suspend/resume sequences


Hi,

On Monday, July 14, 2014 11:54:48 AM Tomasz Figa wrote:
> Hi Kukjin,
> 
> On 25.06.2014 13:52, Tomasz Figa wrote:
> > Due to recent consolidation of Exynos suspend and cpuidle code, some
> > parts of suspend and resume sequences are executed two times, once from
> > exynos_pm_syscore_ops and then from exynos_cpu_pm_notifier() and thus it
> > breaks suspend, at least on Exynos4-based boards.
> > 
> > This patch fixes the issue by removing exynos_pm_syscore_ops completely
> > and making the code rely only on CPU PM notifier.
> > 
> > Tested on Exynos4210-based Trats board.
> > 
> > Signed-off-by: Tomasz Figa <t.figa@...sung.com>
> > ---
> >  arch/arm/mach-exynos/pm.c | 23 ++++-------------------
> >  1 file changed, 4 insertions(+), 19 deletions(-)
> > 
> > Changes since v1:
> >  - rebased onto Kukjin's fixes branch.
> > 
> > diff --git a/arch/arm/mach-exynos/pm.c b/arch/arm/mach-exynos/pm.c
> > index 202ca73..f23cc77 100644
> > --- a/arch/arm/mach-exynos/pm.c
> > +++ b/arch/arm/mach-exynos/pm.c
> > @@ -364,11 +364,6 @@ early_wakeup:
> >  	return;
> >  }
> >  
> > -static struct syscore_ops exynos_pm_syscore_ops = {
> > -	.suspend	= exynos_pm_suspend,
> > -	.resume		= exynos_pm_resume,
> > -};
> > -
> >  /*
> >   * Suspend Ops
> >   */
> > @@ -438,22 +433,13 @@ static int exynos_cpu_pm_notifier(struct notifier_block *self,
> >  
> >  	switch (cmd) {
> >  	case CPU_PM_ENTER:
> > -		if (cpu == 0) {
> > -			exynos_pm_central_suspend();
> > -			if (read_cpuid_part_number() == ARM_CPU_PART_CORTEX_A9)
> > -				exynos_cpu_save_register();
> > -		}
> > +		if (cpu == 0)
> > +			exynos_pm_suspend();
> >  		break;
> >  
> >  	case CPU_PM_EXIT:
> > -		if (cpu == 0) {
> > -			if (read_cpuid_part_number() ==
> > -					ARM_CPU_PART_CORTEX_A9) {
> > -				scu_enable(S5P_VA_SCU);
> > -				exynos_cpu_restore_register();
> > -			}
> > -			exynos_pm_central_resume();
> > -		}
> > +		if (cpu == 0)
> > +			exynos_pm_resume();
> >  		break;
> >  	}
> >  
> > @@ -478,6 +464,5 @@ void __init exynos_pm_init(void)
> >  	tmp |= ((0xFF << 8) | (0x1F << 1));
> >  	__raw_writel(tmp, S5P_WAKEUP_MASK);
> >  
> > -	register_syscore_ops(&exynos_pm_syscore_ops);
> >  	suspend_set_ops(&exynos_suspend_ops);
> >  }
> > 
> 
> Please consider this patch for next fixes pull request. Without it
> suspend/resume is broken for Exynos4 and probably other SoCs. This patch
> just restores the sequence from before the patch moving things to PM
> notifier, so I don't think it should need any special treatment.

Your patch fixes the regression and is a step in the good direction but it
seems that it needs a bit more work:

Your patch adds to cpuidle AFTR code path restoring of exynos_core_save and
exynos5_sys_save registers without saving them first (restoring is done
through exynos_pm_resume() which is used by both suspend and cpuidle while
saving is done through exynos_pm_prepare() which is used only by suspend). 

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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